US2320201A - Electrical conductor - Google Patents

Description

' of station wires and cables.

Patented May 25, 1943 ELECTRICAL CONDUCTOR Julius A. sum-d, name, N. Y., assignor to General Cable Corporation, New York, N. Y., a .cor-

lmration of New Jersey Application August 3, 1940, Serial No. 350,459.-

19 Claims. (Cl. 174-421) This invention relates to mold-proof and rotproof non-metallic coverings, particularly those adapted for use as insulating and protecting jackets for electrical conductors, and the invention has for its principal object the improvement'of such conductors as well as the insulating and protective jackets therefor.

For a long time there has been a great need for a low cost substance suitablefor use in saturants and finishers for non-metallic conductor jackets or sheaths which will be highly resistant to mold (fungus growthlas well as to rotting (decomposition in presence of bacteria) and which will blend readily with the saturants and finishers without affecting their properties in general and their resistance to weathering and aging in particular.

From a practical angle rotting is, as a rule, more dangerous because it may completely destroy th outer'coverin'gs of a cable. Cases are known where in barns, stables and other similar places the entire outer coverings of nonmetallic sheathed cables rotted away in a relatively short time. These outer coverings frequently consists of cotton braid, saturated and finished with asphalt and stearin pitch compounds, overlying folded kraft paper armor treated with parafiin. .At times only the cotton braid rotted away, but in more severe cases even the paper armor and the paper or cotton braid, which is below it, became rotten. In some cases there was a very definite mold growth on the surface of the rotten outer cove gs.

Mold growth" without rot quently in warm damp-places like the conduits in power houses and substations, where no decaying organic matter is present. Thismay be ob served on either the dry or the saturated braids The mold may be only on the surface, in which case it is comparatively harmless, or it may penetrate below the finishing coat and slowly destroy the cotton braid. It is this latter type of mold growth which may cause serious damage to cables. If

permitted to go unchecked, it may destroy the.

entire outer coverings.

Furthermore, electrical conductors are required to be made fiameand fire-resistant, which is customarily accomplished by saturating or coating one or more of the fibrous jackets or coverings with a stearin pitch compound.

One of the principal aims and objects of the present invention is the provision, of an inexpensive compound which may be used alone, or

many non-metallic sheathed occurs frecombined with customarily used moisture-proofing saturants or flame-resistant finishing -cornpounds, and which will be highly eiiective as a mold and rot inhibitor for use in non-metallic sheathed electrical cables.

According tothe present invention, this need is satisfied by the use of the'still residue of diphenyl-oxide distillation containing phenolic compounds, including alkali metal phenolates. This tarry residue may be used alone, or combined with customary asphaltic saturants, as a saturant for insulating bodies, or it may be compounded with customary stearin pitch finishing compounds. This still residue is inexpensive of use and highly eiiective as a mold and rot inhibitor-sin electrical cables.

A specific embodiment of the invention comprehends the use of the tarry residue obtained during the distillation of 'diphenyl-oxide as a mold and rot inhibitor on the fibrous Jackets or coverings of electrical cables which may be sub- Ject to mold or rot. This tarry residue has been known for some time, but-has been considered a waste material. So far as I know, it has never been used or suggested for use heretofore as a I 7 CcHaCcI-l's.

In addition it contains water soluble alkali metal salts of phenolic materials, mostly sodium salts like sodium phenolate, CcHsONa, sodium ortho-phenyl phenolate CsHmGsHANfl and others. These alkali metal salts amount to about 20% of the total. These are water soluble and since a certain water solubility is required for effective fungicidal and germicidal action against fungi and bacteria occurring on wet or damp places, these sodium salts and notably sodium phenolate represent the most active ingredient of this still residue. I

This still residue is a dark colored tarry compound, with properties similar to a bituminous compound. It is tacky at room temperature, but is quite brittle at low temperature. It melts at C. and is quite fluid at -100 C.

At,100- C. it impregnates cotton and other fibrous materials readily. Its flash point is at 145 C. and its fire point at 165 C. Like a great number of bituminous compounds, this still residue has a certain amount of cold flow. It also has a certain oil resistance. When ignited it burns readily, but has some tendency to 'coke. This permits its use in stearine pitch base bituminouscompounds which have fiame resistance due to their choking properties. This still residue may vvary somewhat in physical properties depending on the distillation process, but the above characteristics are typical.

As a compound for use in the manufacture of electrical cables the principal virtues of this still residue are its excellent mold and rot resisting properties; its impregnating qualities for cotton, its compatibility with moistureproof asphalt saturants, its compatibility with flame and moisture resistant stearine pitch compounds and finally its low cost.

Theinvention may be embodied in the manufacture of electrical cable in a variety of ways,

depending upon the use to which the cable is to be put. For example, it may be used alone as a saturant for cotton, jute or other fibrous layers in the interior of the cable structure where adhesion between layers is desired. It can not be used alone on the outside of the cable unless a cable. I have found that this still residue may 4 be combined with any of the saturating compounds in amounts of 1550%. The addition of this still residue will make these saturants rot and mold resistant.

Due to its oil resistance this still residue does not readily blend with some of the more viscous petroleum asphalts. I found that in such cases the addition of 5-10% of montan wax or rosin helps to form a homogeneous blend of asphalt and still residue.

A second group of saturants' used in'the cable industry are known as flame retardant compounds; these are based on stearine pitch because of the good coking properties of this material. Stearine pitch too, is blended with montan wax, petroleum waxes or other modifying agents and is used in this modified form. I

stearine pitch compounds with the still residue.

In addition to the saturating compounds the cable industry uses hard finishing compounds over the saturants to improve appearance and the handling properties of the cable. These finishers usually have a melting point range of 180-220" F. anda penetration at 77 F. of 4-10.

These are either mixtures of petroleum asphalts or. native asphalts like gilsonite with waxes like montan, paraffin, etc., or they are based on stearine pitch modified with native asphalt and waxes.

I ha"e found that this still residue may be combined with either type up to 10-25% and that the addition of this still residue will make either type of finisher rot and mold resistant.

The following is an example of a rot and mold resistantalso flame and moisture resistant finisher:

' Pounds Hard stearine pitch F. M. P.) 45 Gilsonite 25 Montan wax r 10 Still residue 10 Paraflin 10 For all types of fibrous coverings, jackets, wrappings, felts or braids which are used on cables and may be subject to attack by mold, rot,

termites and the like, the use of saturants and finishers containing this still residue will give protection against rot, mold, termites and the like. I

Illustrative of the wide range of uses of the invention, reference is made to the accompanying drawing showing several forms of conductor embodying the invention, in which: p

Fig. 1 is a side view of one form of non-metallic covered conductor embodying the invention;

Fig. 2 is a similar view of a modified form thereof;

Fig. 3 is a side view of a non-metallic sheathed cable construction embodyingthe invention; and

Fig. 4 is a side view of one form of underground cable embodying my invention.

In the variousvfigures the outer coverings are cut away successively 'to show the structure underneath, and the numeral l0 represents the core, which may be solid or stranded, and II the'insulation thereover, which may be a rubber compound, synthetic resin or saturated fibrous insulating material.

In the construction shown in Fig. 1, the insulation ll may be provided with an overlying non-metallic jacket 12, subject to attack by mold,

10% to 25% of the still residue provides a smooth, non-sticky; moldand rot-resistant finish for the cable.

'Instead of incorporating the fungicide with the finish coating, as in Fig. 1, it may be mixed with the saturant, either an asphaltic moistureproof saturant or a flame-resistant stearin pitch, as illustrated in Fig. 2. In such cases up to 15% to 30% of the still residue may be mixed with the saturant l3 to render the jacket I2 moldand rot-resistant.

In the form of invention shown in Fig. 3, a plurality of insulated conductors I0 may be individually covered with a paper-cotton braid as at I 5 and enclosed in a protective tape wrapping, for example paper. The assembled conductors are enclosed by a paper dam i6 and an overlying nonmetallic fibrous jacket 11 which is subject to attack by rot and mold. The braid Il may be provided with a. conventional saturant, such as a fireand moisture-resistant stearin pitch and with a coat of finisher containing from 10% to 25% of the still residue. Alternatively, 'the saturant for jacket I! may be compounded with 15% to 50% still residue'as'in the case of the cable shown in- Hg. 2, in'which case the finish coat may be of any convenient type.

In the case oi. imderground cables, illustrated in Fig. 4,.the insulated conductor it may be wrapped or braided with cotton, jute, sisal or other fibres it, which may be saturatedas at II with the still residue when tackiness is not objectionable, or with a mixture of bituminous compounds containing from 15% to 50% of the still residue. Also it is feasible to presaturate the cotton, jute, sisal or other fibres and apply the presaturated fibres to the cable.

I have found that the inclusion of still residue inthefinisher of from to 25%, or in the saturating compound of from to 50%, produces a conductor which not only withstands mold growth and is perfectly preserved after four weeks of incubation at C. seeded with chaetomium globosum, but in which the cost of saturating and finishing the braid is substantially reduced due tothe cheapness of the still residue as compared with the cost of the usual saturating and finishing materials.

I am aware that heretofore many mold and rot inhibitors have been known and used, or suggested for use, for proofing textile and fibrous bodies, such as sulphur and copper salts and aldehydes. The cost of using these materials, however, was prohibitive except'where it was possible to use inexpensive residual coal tar compounds which hav good moldand rot-resistance and which may be used in certain underground cable construction. However, for non-metallic sheathed electrical conductors, coal tar compounds cannot be'used because these compounds are not flame-resistant, do not age well above ground and cannot be mixed well with customary stearin pitch finishing compounds.

The insulated conductor constructions shown sulated conducting core. a mold and rot resistant sulated conducting core and a mold and rot resistant fibrous jacket therefor saturated with the phenolic tarry residue of diphenyl oxide distillation.

2. An electrical conductor comprising an insulated conducting core and a mold and rot resistant fibrous jacket therefor saturated with alated conducting core and a mold and rot resistant fibrous jacket therefor saturated with a moisture-resistant and flame-resistant stearine pitch base saturant containing 15% to 30% of the phenolic residue of diphenyl oxide distillation.

5. An electrical conductor comprising an insulated conducting core and a fibrous jacket therefor saturated with a moisture-resistant arid flame-resistant stearine pitch base saturantcontaining 3% to 6% of sodium phenolate. contained in the residue of diphenyl oxide distillation and mixed in this form with the stearinic pitch of the saturant to render the fibrous jacket .mold and rot resistant.

'6. An electrical conductor'comprising an infibrous jacket and. a finish coating therefor of in the drawings are merely illustrative of the various applications of the invention, and it will be understood that the phenolic compound containing an active sodium salt of phenol, for example the still residue hereinabove described, may be used alone, or combined with the saturant and waxes in desired proportions, depending upon the particular use for which the cable is intended.

As sodium phenolate is one of the active ingredients of the still residue similar results can be obtained by mixing sodium phenolate with the various saturants and finishers. However, since it is easier and cheaper to blend the still residue. which is a bituminous material with similar bituminous compounds than it is to mix pure sodium phenolat-e with the bituminous compounds I prefer to use the still residue which in addition is much lower in cost than equivalent amounts of sodium phenolate would be.-

It is customary when saturating fibrous materials with bituminous compounds to keep the 'emperature below 350-400 F. because above that temperature the strength of the fibrous material is adversely aiiected by the high temperature. This holds true for the saturating compounds containing the still residue; these should therefore not b used as saturants over 400 F.

It should be also noted that both the saturant and finisher may contain the still residue.

It will be undestood that the invention may be variously embodied within the limits of the prior art and the scope of the subjoined claims.

I claim: I

1. An electrical conductor comprising an in- 25% of the phenolic tarry an asphalt-wax base finisher containing 10% to residue of diphenyl oxide distillation. a I

'1. An electrical conductor comprising an insulated conducting core, a fibrous jacket and a finish coating therefor of an asphalt-wax base finisher containing 2% to 5% of sodium phenolate contained in'the residue of diphenyl oxide distillation and combined in this-form with the asphalt wax used in the finisher to render the finisher mold and rot resistant.

8. A mold-resistant and rot-resistant electrical conductor comprising a conducting core and a fibrous jacket therefor treated with the phenolic tarry residue of diphenyl oxide distillation.

9. A mold-resistant and rot-resistant electrical conductor comprising a conducting core and a fibrous jacket therefor treated with a. still residue jacket of an electrical conductor comprising the phenolic tarry residue of diphenyl oxide distillation.

11. A saturant for rendering moisture-resistant, mold-resistant and rot-resistant the fibrous protective jacket of an electrical conductor comprising an asphalt base and 15-50% Y of the phenolic tarry residue of diphenyl oxide in this form with the asphaltic materials of said base. a I

13. A saturant for rendering flameand moisture-resistant and also 'moldand rot-resistant the fibrous protective jacket of an electrical conductor comprising a stearine pitch base containing 15-30% of the phenolic tarry residue of diphenyl oxide distillation blended with the stearine pitch base by 53-10% of rosin or montan wax.

14. A saturant for rendering fiameand moisture-resistant and also moldand rot-resistant the fibrous protective jacket of an electrical conductor comprising a stearine pitch base combined with 3-6% of sodium phenolate contained in the residue of diphenyl oxide distillation and mixed in this form with the stearinic pitch materials of said base.

15. A finisher for rendering moldand rotresistant the fibrous protective jacket of an electrical conductor comprising an asphalt-wax base containing 10-25% of the-phenolic tarry residue of diphenyl oxide distillation blended with the asphalt-wax base by 5-10% of montan wax.

16. A finisher for rendering moldand rotresistant the fibrous protective jacket of an electrical conductor comprising an asphalt-wax base combined with 2-5% of sodium phenolate contained in the residue of diphenyl oxide distillation and mixed in this form with the asphaltwax materials. of said base.

17. A finisher for rendering fiameand moisture-resistant and also moldand rot-resistant the fibrous protective jacket of an electrical conductor comprising a stearine pitch base containing 10-25% of the phenolic tarry residue of diphenyl oxide distillation blended with the stearine pitch base by 5-10% of montan wax.

18. A finisher for rendering fiameand moisture-resistant and also moldand rot-resistant the fibrous protective jacket of an electrical conductor comprising a stearine pitch base combined with 2-5% of sodium phenolate contained in the residue of diphenyl oxide distillation and mixed in this form with the stearinic pitch materials of said base.

19. A treating material for rendering fibrous materials mold-resistant and rot-resistant comprising the phenolic tarry residue of diphenyl oxide distillation.

JULIUS A. SZILARD.

I CERTIFICATE OF CORRECTION. Patent No. 2,520,201. May 25, 1915.

.mmus A. SZILARD.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, first column, line 8, for "choking" read -'-cokingline 35, for '2O-5O." read --20-hO.--; and that the said Letters Patent should be read with this correction therein that the same z nay conform to the record of the case in the Patent Office.

Signed and sealed this 29th day of June, A. 1).. 1915.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

. Patent No. 2,320,201 May 25, 19!;5.

JULIUS A. SZILARD.

It is hereby certified that err-er appears in the printed speeificetion of the above numbered patent requiring correction as follows: Page 2, first co1umn,'1ine 8, for "choking" read --coking-; line 55, for-"20-50. read I 20-1|.O.--- and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office Signed and sealed this, 29th day of June, A. n; 1915.

,Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

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